Could you please provide a working sample that can be easily modified and used. So json/xml conversion happens dynamically for all rest calls right. Could you please elaborate internal structure and working conditions required to run a new rest service calls using sample code.

I have created a short into how to call REST service with GenericParallel here.

To your questions, no, JSON conversion is not happening. The payload is preserved and passed to the backend as is. The XML GPSRequest/Request wrappers are just to carry the non-XML payload through split-join which doesn’t support non-XML on its own.

All you need to call a REST service in parallel is to have a business service pointing to that REST service, and provide GenericParallel with the payload (JSON or otherwise) and REST properties (relative URI, HTTP method, content-type, …).